Apparatus for the solution by optical means of data capable of representation in the form of triangles



Aug. 20, 1929. J w FRENCH 1,725,070

APPARATUS FOR THE SOLUTION BY OPTICAL. MEANS OF DATA CAPABLE OF REPRESENTATION IN THE FORM OF TRIANGLES Filed Nov. 22, 1927 5 Sheets-Sheet l FiG.1. A

147 NRA/E )5 Aug. 20, 1929. J FRENCH 1,725,070

APPARATUS FOR THE SOLUTION BY OPTICAL; IEANS OF DATA CAPABLE OF REPRESENTATION IN THE FORM OF TRIANGLES Filed Nov. 22, 1927 5 Sheets-She et 2.

n L 34 1F 5 13 zxvvs/vrok nrrop/vevg Aug. 20, 1929. J w FRENCH 1,725,070

APPARATUS FOR THE LUTION BY OPTICAL. MEANS OF DATA CAPABLE OF REPRES NTATION IN THE FORM OF TRIANGLES Filed Nov. 22, 1927 5 Sheets-Sheet 5 mmwmmmmz AWE/V78? jaw 25,, 52M

Aug. 20, 1929. J w FRENCH 1,725,070

APPARATUS FOR THE SOLUTION BY OPTICAL MEANS OF DATA CAPABLE OF REPRESENTATION IN THE FORM OF TRIANGLES Filed NOV 22, 1927 5 Sheets-Sheet 4 Aug. 20, 1929. J w FRENCH 1,725,070

APPARATUS FOR THE SOLUTION BY OPTICAL MEANS OF DATA CAPABLE OF RE RESENTATION IN THE-FORM OF TRIANGLES Filed Nov. 22, 1927 5 Sheets-Sheet 5 H TOP/VEY Patented Aug. 20, 1929.

UNITED STATES PATENT OFFICE.

JAMES WEIR FRENCH, F GLASGOW, SCOTLAND, ASSIGNOR TOJBARR AND STBOUD,

' LIMITED, OF GLASGOW, SCOTLAND.

APPARATUS FOR THE SOLUTION BY OYTICAL MEANS OF DATA CAPABLE OF REPRE- SENTATION IN THE FORM OF 'IRIANGLIEQ Application filed November 22, 1927-, Serial No. 235,018, and in Great Britain December 10, 1826.

This invention relates to apparatus for the solution by optical means of data capable of representation in the form of-right-angled and other triangles, the measurements being effected as a result of the movement of an optical image in a field of view capable of observation directly by the eye or indirectly, say by means of an eyepiece; and to mechanism whereby the image can be displaced radially, angular-1y and translationally, say

in accordance with polar, rectangular or oblique co-ordinates for the purpose of setting or measuring the position of the image radially or angularly, or with reference to rectangular or oblique co-ordinate axes or other points of reference in the field of View.

Apparatus constructed in accordance with this invention comprises an optical system whereby an image of va'n'object in afixed plane is formed in a field of view capable of observation directly or indirectly, say by means 0t an eyepiece, together with optical means such as deviating prisms capable of being appropriately displaced and/or rotated whereby the position of the image can be altered in any desired manner in the field of view, relatively to a reference mark, which, for example, may be a centre of reference or a diameter of reference, or rectangular or oblique co-ordinate axes or other position of reference in the field of view.

Some typical examples of apparatus in accordance with this invention will now be described with reference to the accompanying drawings, in 'which:

Figure 1 is an illustration of a field of view showing positions to which an image produced by an optical system may be displaced.

Figure 2 is a diagram illustrating in longitudinal/axial section a first optical system by which the image as in Figure 1 may be J produced and displaced. 4

Figure 3 is an illustration of the field of view, Figure 1, introduced for reference in describing theinvention.

Figure 4 is a diagram illustrating in longitudinalaxial section a part of the first optical system, Figure 1.

Figure 5 is a diagram illustratingin longitudinal axial section a second optical sys tem by which. the image as in Figure 1 may be produced and displaced.

Figure 6 is a, diagram illustrating an example of values to be determined.

Figure 7 is a diagram illustrating in longit-udinal axial section a third optical system for use in determining the values in Figure 6.

Figure 8 is an illustration of a field of Figure 12 is an end elevation of Figure 11.

Figure 13 is a sectional side elevation of a mechanism for relative rotation of two deviating prisms constituting a pair and for their simultaneous rotation.

Figure 14 is a diagrain partly in section of mechanism for the displacement and r0 tation oftwo prisms.

Figure 15 is a diagram partly in section of apparatus comprising an optical system corresponding with Figure 7.

'In Figure 1, A represents theimage at a distance 2 from the optical centre 3 or reference mark in the field of view, the radius A, 3 being inclined at an angle a to say, the horizontal diameter or axis of reference 4, 5 of the field of view. The means provided permit of the image A being set to the required position in the field of view, and, further,

enable the distance 6 of the image A from t the horiontal axis 4, 5 or the distance 7 from the vertical axis 8, 9 to be determined.

In Figure 2, 10-is an illuminating lamp, 11 a graticule having engraved upon it an object B,r.sa v a small cross, 12 is a projector lens which forms an image A of the object B in the image plane 13 viewed by an e epiece 14. 15 is a. deviating prism capa 1e of longitudinal movementbetween the object B and the projector lens'12 and capable also of being rotated in a plane normal to the optical axis. With the prism 15 displaced, say into the position indicated in Figure 2, theiimage A may be displaced in the field 13 radially with respect to the reference mark 3 into the position shown in Figure 3, the radial angle a being deterrange, the position of the mined by the orientation of the prism 15 about the optical axis. If, for example, the deviating prism 15 were rotated, the image A, Figure 3, would trace out a circular path. For any particular orientation. as the prism 15 is moved towards the lens 12, the image A moves radially out from the mark 3 and conversely, as the prism is displaced towards the object B the image A moves towards the mark 3. In the particular arrangement indicated the image A would coincide with the mark 3 if the prism 15 were brought into the plane 11.

For many purposes, such as gunnery purposes, in which case the radial distance in the field of view would correspond, with, say, the range of a target, it is generally unnecessary to considerv ranges less than a definite minimum corrsponding, say, with the position 16 of the image in the field of view, Figure 3. Other arrangements will be described later in which the.image A can, if desired, be displaced radially into the centre of reference. By suitable displacement and rotation of the deviating prism 15 the image A may be set in the manner described to any desired polar co-ordinates corresponding with, say, the range and bearing of a.

target.

In order to measure, say, the distance 7, Figure 1, of the image A from the axis 8, 9, a deviating prism 17 Figure 2, may be providing having its deviation axis disposed parallel to the axis 4, 5 along the direction 4 of which it is desired to make the measurement, the prism 17 being capable of longitudinal movement between the image plane 13 and the lens 12. The initial settings of the optical system should be such that, when the deviating prisms l5 and 17; are set in their positions correspondin say, with zero field of view 13 must be such that the image A of the object B coincides with the centre or reference mark 3 of the field, as indicated in Figure In any further descriptions such initial.

adjustments will not be described or indicated. The systems will be represented diagrammatic-ally only as in the ease of Figure 2.

. In the arrangement, Figure 4, it is assumed that the prism 17 is capable of measuring zero values and that the zero position of the prism does not coincide with the field 13. If, after the system has been initially adjusted, the deviating prism 15, Figure 2, is moved from its zero or minimum position towards the lens 12 and rotated by the required amount, the image A will be set in the field 13. as indicated in Figure 3 and as previously described. If the prism 17, whose deviating axis is parallel to the axis 4, .5,

Figure 1, is moved longitudinally without being rotated, the image A may-be displaced horizontally until it coincides with the vertical axis of co-ordinates 8, 9; that is to say, the logitudinal displacement of 17 afiords a measure of the distance 7. If the (:o-ordinate distance 6 of A from the axis 4, 5 is desired, the prism 17 may be rotated in the appropriate direction through and be disposed as before to the required extent. If the axis, say, 8, 9 is obliquely displaced with respect'to 4, 5 the prism 17 may be rotated by a corresponding amount such that its deviation axis is parallel to the particular axis along which the measurement is desired.

Instead 'of rotating the prism 17 into various positions according to the nature of the measurement required, it may be arranged that the prism 17 moves longitudinally with its deviation axis in one definite co-ordinate plane and an additional optical system may be provided, see Figure 5, comprising, .say,

a projector lens 18, a focal plane 19 viewed as before, together with a deviating prism 20 capable of longitudinal dipslacement, the prisms 17 and 20 being so disposed that the deviation axis of one moves arallel to one of the co-ordinate planes an the deviation axis of the othei parallel to the other coordinate plane. By suitable movement of 20 and 17 the image A, Figure 1, can be moved vertically with respect to the axis 4, 5, and horizontally with respect to the axis 8, 9 and by these means it may be made to coincide with the position of the centre 3.

As another example illustrating the application of this invention an arrangement constructed in accordance with this invention shall be described, see Figure 6, whereby from the measured range 21 of a target 22 from, say, a rangefinder position 23 and v from. the known distance 26 between the said rangefinder and, say, a gun position 24 and from the measured angle 6- between the direction 22, 23 and 23, 24 there may be determined the range 25 from the gun 24 to the target 22 and also the gun bearing angle a; that is to say, it is desired to solve the triangle, Figure 6, the sides 21 and 26 of which are known together with the angle b, and in which triangle the value of the side 25 and the angle 0 are to be determined. For the solution of such a triangle the elements indicated in Figure 7 may: be employed, in

- of longitudinal displacement from a zero polected,-theprism may be displaced and rotated by amounts corresponding with the distance 21 and the angle 5 respectively, with the result that the position of the image A in the field of view, Figure 8, with respect to.

the centre 3 and the horizontal diameter, 4, 5 will correspond in direction and magnitude with the position of the target 22 relatively to the line through the gun and rangefinder positions 24 and 23 respectively and relatively to the rangefinder position 23.;

If the eflect of prism 20 is for the moment neglected and if prism 27, which is assumed to be so arranged that it will deviate the beam in the appropriate direction as indicated in the diagram, is setwith its deviation axis in the horizontal plane parallel to the diameter 4, 5, which as previously stated may be regarded as being parallel to the side 23, 24 of Figure 6, the image A may by a suitable longitudinal movement of the prism 27 be displaced towards the right into a position 28 such that the horizontal distance from A to 28 corresponds with the distance 26 of Figure 6; that is to say, the distance of the rangefinder station-from the gun station.

It will be evident that the distance from 3 to 28, Figure 8, will correspond with the distance 25, Figure 6, the determination of which is required, and that the angle between the lines 3, 28 and 3, 5 will be the angle a of Figure 6 which is required to be determined. The angle 0 may be determined by a suitable rotation together as one unit of the prisms 1 5 and 27, the directi'on'and amount of the rotation being such that the point image 28 is rotated downwards until it intersects the diameter 4, 5. The value of the necessary angle of rotation can be indicated, say, upon dials or transmitted to the gun or other stations, where it can be used either directly or indirectly in the aiming of the guns.

In order to determinethe distance 25, Figure 6, which corresponds with the distance from 3 to 29, Figure 8, the deviating prism 20 whose deviation axis lies in the horizontal plane which also contains the diameter .4, 5

I is so displaced as to move the image 29 into the position 3 in the field of view'. The amount of displacement of the prism 20 at fords a measure of the distance 25, Figure 6, and the amount can be indicated, say,

upon dials or transmitted to other stations for direct or indirect use in the aiming of the .gun. It will be observed that inthis particular example the final measurement is effected by bringing the image of the object B into the'position of reference mark 3 by appropriate angular and longitudinal movements of the deviating prisms.

In place of deviating prisms which displace the image as a result of their longitudinal movement, pairs of prisms may be employed which can be rotated relatively to one another so as to vary the deviating power of the pair and which may be rotated in the plane of the prisms about the optical axis of the system for the purpose of rotating the image in the field of view. As an example of the application of this invention, apparatus of a typical kind in which such pairs of prisms are employed is represented in Figure 9, in which 10 is the illuminating lamp, B the object engraved on graticule 11, 12 a projector lens, l3'the field of view, 30 and 31 two deviating prisms capable of being rotated by equal amounts in opposite directions relatively to one another, whereby the deviating power of the pair is varied without altering the direction of the deviation axis of the pair, and capable of being rotated together for the purpose of varying the direction of the deviation axis. 32 and 33 constitute another pair of prisms capable of being rotated in a similar manner relatively to each other but in this particular example no provision is made for rotating the prisms together. The'elements indicated in Figure 9 perform the same general function as those indicated in Figure 2; that is to say, if the prisms 30 and 31 are. rotated relatively to each other by equal and opposite amounts, the deviating power of the combination may be varied from a maximum to zero and thereby the image A, Figure 3, may be moved from an extreme outer position into coincidence with the centre 3. Suppose the prisms are so rotated relatively to each other that .\-the image occupies the position shown at A Figure 3. By, rotating the two prisms together in the-appropriate direction any desired rotation of the image A can be effected. If, for example, it is rotated until it lies upon the axis 4, 5 the amount of rotation of the prism combination afiords a measure of the angle a. If the deviation axis of the combination 32, 33 is always maintained parallel to, say, the diameter 4, 5', Figure 1, an alteration of the power of the combination by rotating the prisms 32 and 33 by equal amounts in opposite directionsenables the image A to be displaced parallel to the diameter 4, 5 and, that the image A is brought into coincidence if the displacement is such' with the vertical diameter'8, 9, the amount of the relative displacementaffords a measure of the distance 7.

Other optical elements may be employed such as prisms, the rotation and angling of which enable the image in thefield of view to be rotated and displaced. A typical example of such an arrangement constructed in accordance with this invention is illustrated in Figure 10, in which 10 is, as before, the lamp, B the object engraved on 'graticule 11, say a deviating prism-capable of longitudinal displacement but not in this particular example of rotation in its own plane, the deviation axis of the prism being appropriately set with regard to the axis of reference in the field of View; 12 is a projector lens, 13 the'field, and 34 is, say, a right-angled prism capable of rotation about the optical axis 12, 35, the prism being rov tated'together with the parts 10, 11 and 15,

all in a plane normal to the axis 12, 35. By suitable longitudinal displacement of the prism 15, the image A, Figure 3, can be moved radially from a maximum to a minimum position. By rotation of the parts above described in a plane normal to the axis 35, 12, the image A can be rotated in the field of View about the centre 3. A de- "g Other known arrangements of reflecting prisms and prism combinations or combinations of reflecting prisms and deviating prisms may be employed according to the conditions and to the degree of accuracy in the measurements that isdesired.

A- typical example of means in accordance with this invention for the rotation and dis-, placement of a deviating'prism such as the prism 15 of Figure 2 is illustrated in Figures 11 and 12, the former being, say, a plan and the latter an end elevation. Rotation of the prism 15 is efiected as follows: when, say, the head 36 is rotated, the pinion rod 37 associated with the head rotates the holder 38 and deviating prism 15, the periphery of the holder being provided with suitable teeth in mesh with the pinion rod. The prism is translated longitudinally as follows: when, say, the head 39 is rotated the screw 40 associated with the head translates the nut 41 mounted upon the screw 40 and with it the carrier 42 and the prism 15; the teeth of 38 being free to move along the pinion rod 37 A. guide rod 43 which engages a slot at the end of the carrier '42 prevents any rotation of the carrier and prism as the result of the rotation of the screw 40.

Typical means in accordance with this invention for the relative rotation of two deviating prisms constituting a pair and for their simultaneous rotation, as is required for example for the operation of prisms 30 and '31, Figure 9, are illustrated in Figure 13. where 30 and 31- are the prism of, say,

Figure 9. Simultaneous rotation of the prisms 30 and 31 by the same amount and in the same direction is effected by rotation, say, of the head 44. The action is as follows: when the head 44 is rotated, say

.which is so mounted as to be capable of rotation upon the carrier 48, will rotate in a counter-clockwise direction, that is, in the same direction as the toothed periphery 47; it will also move by the same amount since the ratio between the wheels 45 and 47 is arranged to be the same as the ratio from 46 through 50 to 51 and thence to 54; that is to say, the elements 54 and 47 will move together as if they were in one piece toether with the carrier 48 and the prisms 30 and 31 which in their rotation together as one pair about the longitudinal axis'55, 56 will not be relatively rotated. By means of, say, the handle 53 prisms 30 and 31 may be relatively rotated by equal amounts in opposite directions for the purpose of altering the deviation power of the pair without as the result of this operation altering the position of their resultant deviation axis. The action is as follows: if the handle 53 is rotated, say in a counter-clockwise direction when viewed from the right, the spur-wheel 57 rotates counter-clockwise, 52 rotates clockwise, 51 rotates clockwise, and' the floating wheel 54 is rotated in a counter-clockwise direction relatively to the carrier 48. Since the handle 44 may for the purposes of this operation be considered held, thev toothed periphery 47 and the carrier 48 will also be held. Therefore the element 54 in rotating relatively to 48 will drive the wheels 58 and 59 mounted in the held element 48 in a counter-clockwise direction. The pinion 60 mounted upon 48 will be driven in a clockwise direction and the toothed periphery of the holder 61 carrying the prism 31 will rotate in a counter-clockwise direction when viewed from the right. The wheel 59 moving in a counter-clockwise direction will rotate the toothed periphery of the holder 62 carrying the prism 30 in a' clockwise direc-- tion and, since the ratio between 58 and 61 is equal to the ratio between 59 and 62, the

prisms 30 and 31 will not only move in opsuch as 15, Figure 7, is illustrated in Figure 14, which also shows the means whereby prism 27, Figure 7, may also be rotated and displaced and whereby the two rotational motions of the prisms and 27 may be associated for the purpose of solving the triangle represented in Fi ure 6. Displacement of the prism 15 is e ected by rotation of the handle 63. If this handle is rotated in a clockwise direction when viewed from the left, wheel 64 rotates clockwise, wheel 65 carrying the jockey wheel 66 rotates counter-clockwise. It is assumed for this particular operation that differential element 67 is held as regards rotation. Element 68 of the differential and wheel 69 rotate coun- 15 ter-clockwise. The wheel 70, which is so mounted as to be capable of rotation'relatively to its carrier 71, is provided with peripheral teeth and also internal teeth.

. The pinion 72 is mounted on the end of the both elements beingthe same,

screw shaft 73, upon which is mounted the nut 74 carrying the prism 15, the nut and prism being prevented from rotation about the longitudinal axis-relatively to 71 and the parts 72 and 73 being mounted upon 71.

As the wheel rotates relatively'to 71,it,

drives the pinion 72 and through the intermediary of the screw 73 displaces the prism 15 in a longitudinal direction. Rotation of the prism 15 about the longitudinal axis is effected through the intermediary of the handle 75. The action isas follows: when 75 is rotated, say, in a clockwise direction when viewed from the left, differential element 76 moves clockwise; the wheel 7 7 carrying the jockey pinion 78 moves clockwise; wheel 79 moves counter-clockwise; the pinion 80 moves counter-clockwise, and the carrier 71 being provided with peripheral teeth 81 in engagement with 80 is thereby rotated in a clockwise direction. All the parts including the prism 15 mountedupon 71 are thereby rotated in a clockwise direction about the longitudinal axis. The wheel 82' move clockwise and 68 moves counter-clock wise, since the jockey pinion 66 actsas an idle pinion and since 65, so far as theiparticular operation is concerned, ma be assumed to be held by the head 63. Wheel 69 associated with 68r0tates in a counterclockwise direction and the floating wheel 70 rotates clockwise;"that is to say, 70 rotates in the same direction. as '71 and, the gear ratios associated with the rotation of they move together as. if the were in one lece.

I v rotation is, there ore, imparted to 2 and the rotation of 15 about its longitudinal'axis of the head.,75

through the intermediar does not involve any longitudinal movement of the prism 15. I

Identical elements may be employed for the rotation and displacement of prism 27. Simultaneous rotation of the prisms 15 and tates the prism 15 through the intermediary of the differential elements 85, 77 and 76,

the element 76 being assumed to be held so far as this particular operation is concerned by means of the head 75.

The apparatus illustrated at Figure 15, comprises optical parts as represented in Figure 7, for effecting movements of the image represented in Figure 8. Figure 15, shows, illuminating lamp 10, graticule 11, object B, say a cross, on 11, deviating prism 15, lens 12, deviating prism 27, field lens 13, prism 20, lens 18, focal plane 19, reference mark 3 in focal plane 19, and eyepiece 14. Lens 12 forms an image of object .B at field lens 13 and lens 18 transfers the image at 13 to the focal plane 19 where it is examined by eyepiece 14.

Prism 15 is movable with nut 74, nut 74 is mounted on screw 73, screw 73 is movable with sleeve 71, sleeve 71 is rotatable about the axis of the system but otherwise is not movable, screw 73 is rotatable with pinion 72, pinion-'72 meshes with an internal gear of wheel 70, wheel 70 and sleeve 71 are relatively rotatable. Gear wheels 81 and 82 are rotatable with 71. An external gear of wheel 70 meshes with gear wheel 69. Gear wheel 69 is rotatable with bevel gear 68 of a differential 66, 67, 68. Bevel gear 66 is revolvable about the axis of 67, 68, with rotation of gear wheel 65. Gear wheel 65 meshes with gear wheel 64. Gear wheel 64 is rotatable by handle 63. Pointer of dial 95 is movable angularly by rotation of 63. Bevel gear 67 is rotatable with gear wheel 83. Gear 83 meshes with gear 82. Gear 81 meshes with a gear 80. Gear 80 is rotatable with a gear 79. Gear 79 meshes with a gear 77. Gear 77 is rotatable about the axis of bevel gears 76, 85, of a differential 76, 78, 85. Bevel gear 78 is revolvable about the axis of 76, 85 with rotation of 77. Bevel gear 76 isrotatable by handle 75. Pointer of dial 94 is movable angularl by rotation of 7 5. Bevel ear 85 is rotata 1e by handle 84. Pointer o dial 93 is movable angularly by rotation of 84.

Prism 27 is movable with nut 741, nut 741 is mounted on screw 731, screw 731 is movable with sleeve 711, sleeve 711 is rotatable about the axis of the system but otherwise is not movable, screw 731 is rotatable with pinion 721, pinion 721 meshes with an internal gear of wheel 701, wheel 701 and sleeve ,711 are relatively rotatable. Gear wheels Gear wheel 641 is rotatable by handle 631. Pointer of dial 96 is movable angularly by rotation of 631. Bevel gear 671 is rotatable with gear 831. Gear 831 meshes with gear 821. Gear wheel'811 meshes with a gear wheel 801. Gear 801 is rotatable by handle Prism 20 is movable with nut 87, nut 87 is mounted on screw 86. Screw 86, rotat able, but otherwise is not movable, is rotatable with pinion 722, pinion 722 meshes with gear wheel 89. Wheel 89 is rotatable by handle 90. Pointer of diaD92 is movable angularly by rotation of 90.

By rotation of screws 73, 731, 86, prisms 15, 27, 20, respectively, are moved longi tudinally, that is along the axis of the system. By rotation of sleeves 71, 711, prisms 15, 27, respectively, are rotatable about the axis of the system.

Operation of handle 63 causes gears 64, 65, 66, 68, 69, and 72 and screw 73 to be 1 rotated and prism 15 to be displaced longitudinally, the extent of which vis indicated by the pointer of dial 95.

Operation of handle 631 causes gears 641, 651, 661, 681, 691, 701 and 721 and screw 731 to be rotated and prism 27 to be displaced longitudinally, the extent of which is indicated by the pointer of dial 96.

Operation of handle causes gears 76,

78, 77, 79, and 81 and sleeve 71 and with it prism 15 to be rotated and by rotation of sleeve 71, gears 82, 83, 67, 66, 68, 69 and 70 are rotated and cause gear 72 and with it screw 73 not to be rotated, so that by operation of handle 75 prism 15 is rotated with sleeve 71 but is not displaced longitudinally. The extent of rotation of prism 15 is indicated by the pointer of dial 94. Operation of handle" 84 causes gears 85, 78, 79, 80 and 81 and sleeve 71 and with it prism 15 to be rotated, without displacing it longitudinally as already explained, and also causes gears 801, 811 and sleeve 711 and with it prism 27 to be rotated and by rotation of sleeve 711 gears 821, 831, 671, 661, 681 and 701 are rotated and cause gear 72 and with it screw 731 not to be rotated, so that by operation of handle 84 prism 27 is rotated with sleeve 711 but is not displaced longitudinally. Thus, by operation of handle 84: prisms 15 and 27 are rotated similarly, and the extent of this rotation is indicated by the pointer of dial 93.

Operation of handle causes gears 89, 722, and screw 86 to be rotated and prism 20 to be displaced longitudinally, the extent of which is indicated by the pointer of dial 92.

As shown at Figure 8 with this apparatus,

Figure 15, by operation of handle 63 the image A relatively to reference mark 3 is displaceablefradially and by operation of handle 75 it IS displaceable angularly about mark 3.

For example, the image A by operation of handles 63 and 75 may be displaced into the position indicated. By operation of handle 631 the displaced image A is movable parallel with 45, for example, to position 28. By operation of handle 84 the displaced image at 28 is movable angularly about a reference mark 3, for example to position 29. By operation of handle 90 the displaced image relatively to reference mark 3 is movable parallel with 45, for example from 29 to 3.

These values are indicated by the pointers on the-dials as follows: Dial measurement 3A. Dial 94 the angle A, 3, 5. Dial 96 the measurement A28. Dial 93 the angular movement 2829. Dial 92 the measurement 29-3.

' VI claim 1. Apparatus for the solution of data capable of representation in the form of triangles, comprising a stationary object, a

source of light for illuminating the object,

a reference mark, an optical system situated between the object and the reference mark, the optical system having image forming means and image displacing means, the

image forming means being for forming an image of the object at an ima e plane in which the reference mark is situated, the image displacing means being for displacing the image in said image plane, radially, angularly and translationally, and the image plane being a field of View capable of observation.

2. Apparatus for the solution of data capable of representation in the form of triangles, comprising a stationary object, a source of light for illuminating the object, a reference mark, an optical system situated between the object and the reference mark, the optical system having image forming means and image displacing means, the image forming means being a lens system for forming an image of the object at an image plane in which the reference markis situated, the image displacing means being optical parts movable separately and collectively for displacing the image in said image plane, radially, angularly and translationally, and the image plane being a field of view capable of observation.

3. Ap aratus for the solution of data capable o representation in the form of triangles, comprising a graticule, an ob ect engraved on the graticule, a lamp for illum nating the object, a reference mark, an optical system situated between the object and the reference mark, the optical system having image forming means and image dislacing means, the image forming means being for forming an image of the object at an image plane in which the reference mark is situated, the image displacing means being for displacing the image in said image plane, radially, angularly and translationthe image ally, and the image plane being a field of view capable of observation.

4. Apparatus for the solution of data capable of representation in the form of tri angles, comprising a stationary object, a source of light for illuminating the object, a reference mark, an optical system situated between the object. and the reference mark, the optical system having image forming means; and image displacing means, the image forming means being a lens system for forming an image of the object at an image plane in which the reference mark is situated, and the image displacing means being three prisms, each of the three being movable longitudinally and two of the three being rotatable separately or collectively for displacing the image in' said image plane, radially, angularly and translationally, and the image plane being a field of view capable of observation.

5. Apparatus for the solution of data capable of representation in the form of triangles, comprising a stationary object, a source of light for illuminating theobject, a reference mark, an optical system situated between the object and the reference mark,

the optical system comprising in sequence from the object, a first prism movable longitudinally and rotationally, a first lens, a second prism movable longitudinally and rotationally, a second lens, a third prism movable longitudinally, and a third lens, the lenses being for forming an image ofthe object at an image plane in which the reference mark is situated, the prisms being for displacing the image in said image plane, radially, an ularly and translationally, and plane being a. field of view capa ble of observation.

6. Apparatus for the solution of data capable of representation in the form of tri-- angles, comprising a stationary object, a

source of light for illuminating the object, a

reference mark, an optical system situated between the object and the reference mark, the optical system comprising in sequence from the object a first prism, a first lens, a second prism, a second lens, a third prism, and a third lens, the lenses being for forming an image of the object at an image plane in which the reference mark is situated, mechanism for moving the first prism longitudinally and rotationally,mechanism for moving the second prism longitudinally and rotationally, mechanism for moving the first and second prisms rotationally together, and mechanism for moving the third prism longitudinally, the prisms being for displacing the image in said image plane, radially, angularly and translationally, and the image plane being a field of view capable of ob servation.

7 Apparatus for the solution of data capable of representation in the form of triangles, comprising a stationary object, a source of light for illuminating the object, a refer ence mark, an optical system situated between the object and the reference mark, the optical system comprising in sequence from the object, a first prism, a first lens, a second prism, a second lens, a third prism, and a third lens, the lenses being for forming an image of the object at an image plane in whichthe reference mark is situated, mechanism for moving the first rism longitudinally and rotationally, mec anism for moving the second prism longitudinally androtationally, mechanism for moving the first and second prisms rotationally together, and mechanism for moving the third prism longitudinally, the prisms being for displacing the image in said image plane, radially,

- JAMES WEIR FRENCH.

- angularly and translationally, the mage- 

